The incidence of infection after skeletal implant surgery is low, but the disasterous results of these infections make them major complications. In vitro experiments have suggested that some implant materials adversely affect immune mechanisms against infection. The clinical significance of in vitro impairment of immune mechanisms is not known but can be determined in an in vivo experimental model. In the proposed project, implants of polymethylmetracrylate, high density polyethylene, stainless steel, and chrome-cobalt will be placed in the surgically prepared femoral canal of the rabbit following the instillation of log dose dilutions of bacteria. Occurrence of infection will be determined by bacterial culture and the incidence of infection will be expressed as the infectious dose-50. Incidence of infection with the various implant materials will be compared. It is expected that all implant materials, as compared to no implant, will enhance the development of infection when implanted with bacteria. The purpose of the project is to determine if the bone cement, polymethylmethacrylate, enhances the development of infection more than the other commonly used implant materials and to determine if any commonly used implant materials enhance development of infection to a greater extent than the others.